Endovascular medical device with plurality of wires

ABSTRACT

An endovascular device ( 1, 100, 200, 300 ) having a distal end ( 2 ), a proximal end ( 4 ) and a body portion ( 3 ) therebetween. The body portion is made of a multiple filament helically wound row (A) of wires ( 5 ), provided with a sealing coating ( 14 ) on the inside surface or the outside surface or both. The device may be a catheter ( 1 ), a sheath, an introducer, a delivery device, a pusher ( 100 ), an embolization coil delivery device ( 300 ), or a receptacle ( 208 ) for an expandable prosthesis ( 220 ) used with a delivery device ( 200 ). From 2 to 12, and preferably from 4 to 8, wires ( 5 ) are used in the row, and fewer wires may be used proceeding toward the distal end ( 2 ) for greater flexibility. The helically wound row of wires transmits torque and provides pushability to the device while resisting kinking, and enables a small outside diameter for reaching very small vessels and extending through very tortuous vessels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of the following European applications:

Serial No. 00610012.7 filed Jan. 28, 2000

Serial No. 00610013.5 filed Jan. 28, 2000

Serial No 00610014.3 filed Jan. 28, 2000

Serial No. 00610015.0 filed Jan. 28, 2000

TECHNICAL FIELD

The present invention relates to the field of medical devices and moreparticularly to vascular devices such as catheters and delivery systemsfor implantable devices.

BACKGROUND OF THE INVENTION

Catheters for medical diagnostic or therapeutic use are well known. Acatheter has a distal end and a proximal end, with a body extendingtherebetween and a lumen extending therethrough from end to end. A widevariety of catheters exists for percutaneous insertion by the Seldingertechnique into the vascular system to accomplish diagnostic ortherapeutic objectives. The vessels of the peripheral vasculature have arelatively large diameter and low tortuosity, the coronary vasculatureis somewhat smaller and more tortuous, and the vasculature in the softtissue of the brain and liver is of small lumen and is very tortuous.

In order to be able to access the various parts of the vasculature, thecatheter needs to be flexible and to maintain its column strength whenit follows a tortuous path. The contradictory requirements forflexibility and column strength are particularly pronounced in cathetersfor intracranial catheterizations used in a variety of diagnostic andinterventional neurological techniques including delivery of contrastfluids, drugs or a vasoocclusive agent, treatment of tumors, aneurysms,AVS (arteriovenous shunts) and so forth.

When a central member is to be moved within a catheter or sheath toperform an activity at or beyond the distal end of the catheter, afterthe catheter has been positioned, the central member is to be pushedthrough the catheter lumen. The more tortuous the path and the smallerthe catheter the more difficult it is to advance the central memberthrough the catheter lumen. This difficulty is in particular pronouncedin coaxial systems for intracranial use. Where the central member is adelivery device for an embolization coil and must be rotated todisconnect from the coil upon release at the treatment site, the centralmember must be capable of transmitting torque to its distal end forassured coil disconnection; one such prior art coil delivery system isdisclosed in U.S. Pat. No. 5,122,136; but it is a common problem thatsuch prior art coil delivery members have relatively high rigidity whichis problematic in small or tortuous vessels with aneurysms. Where thedevice is a pusher to push a device such as a stent from the distal endof the catheter, the pusher must have substantial column strength aswell as great flexibility.

Where a catheter is to be used for delivery of an endovascularprosthesis to a treatment site, such as a stent, a stent graft, a valvemember, or a filter, where the prosthesis is compressed to pass throughthe catheter and then selfexpand upon release therefrom within a bodylumen, the prosthesis must be constrained while within the catheter andimposes significant forces against the surrounding catheter body.

It is an objective of the present invention to provide a medical devicethat includes a distal area that is very flexible and yet easilypushable and capable of transferring torque in an assured, controllablemanner.

It is another objective to provide a catheter system that makes iteasier to advance the central member through the catheter also in caseswhere the catheter exhibits sharp turns.

It is further an objective to provide a catheter that resists thesubstantial radially outward forces of a compressed endovascularprosthesis contained within the distal end thereof, and yet be veryflexible and capable of transferring torque.

It is yet another objective to provide a central member for movementwithin a catheter lumen that is very flexible, has substantial columnstrength and/or is capable of transferring torque.

BRIEF SUMMARY OF THE INVENTION

The foregoing and other problems are solved and a technical advance isachieved in an illustrative medical device for passage along thevasculature of a patient, having a body portion comprising primarily aplurality of coils or turns of a plurality of wound filaments or wires.The medical device may be a catheter or may be one or more components ofa delivery system for endovascular devices, such as a central memberwithin a catheter, for example, a pusher or delivery device for anembolization coil. Two to twelve filaments such as wires, and preferablyfrom four to eight wires, are preferably helically wound adjacent toeach other as a group or row with a pitch corresponding generally to theaggregate width of the adjacent wires in the row.

The wound wires transfer torque and also force components directed inthe axial direction of the medical device to the distal end thereof, andthis construction is found to give a very high resistance to kinking ofthe medical device. When a catheter according to the present inventionis heavily bent, the cross-section of the catheter maintains a circularshape. This provides a distinct advantage over prior art catheters whichare deformed into an oval shape in cross-section when bent leading tokinking. The catheter surprisingly maintains its capabilities fortransferring torque and push when it follows a tortuous path involvingtwo or more loops, probably because of the excellent kinking resistance.These qualities facilitate placement of the catheter at the desiredposition in the vascular system, and by making the catheter system sothat the inner surface of the catheter is mainly undeformable by acentral member moving axially therewithin, it is virtually impossiblefor the central member to get stuck in the catheter wall, even insituations where the catheter is heavily curved. This is in contrast toprior art coaxial systems where the catheter is made of a soft materialsuch as a resin, the inner surface of which is readily deformable in alocal area, causing the formation of a small bead in front of the tip ofthe central member bearing against the wall of the curved catheter. Itis an advantage of the catheter according to the present invention thatthe wall is primarily made of wires that provide a hard and relativelyslippery inner surface resulting in low resistance to advancing thecentral member through the lumen of the catheter.

The inventive catheter maintains three valuable characteristics of veryhigh flexibility, pushability and torqueability even when set in a verytortuous pattern involving two or more tight loops, and the catheter canthus be of use in very small and distant vessels such as deep brainsites accessed by intracranial catheterization. Preferably, a thinsealing coating of elastic, low-friction material, or adhesive materialmay be provided over the outwardly directed surfaces of the coiled wiresor along the inner surfaces that define a lumen, or at least in recessesbetween abutting wires or in interstices between nonabutting turnsbetween the groups of wires, thus sealing the interstices between thewires so that the catheter wall is leakproof especially where the deviceis a catheter or sheath.

Further, wires may have the same diameter in the group and extend theentire length of the device, or the device may have portions with wiresof different diameters, lessening toward the distal end and therebydecreasing gradually in outer diameter; the device may also have anoncoiled part in the proximal region such as a supplementary cannula ortubing.

In the present context, the term Acatheter@ is to be understood in thesense that it can be an ordinary catheter, but also a sheath, which is ashort catheter, and in the latter case the central member can be acatheter, e.g., a catheter according to the present invention. Thesheath can have a check-flow valve or a fitting at the proximal end inorder to stop bleeding out of the puncture site. In one aspect, thecatheter may be utilized without a guidewire. When intended for use in asoft tissue region, it is preferred that the distal end of the catheteris provided with a buffer member, such as a soft obturator, thatdistributes the force from the catheter tip over a large area so thatdamage to the vascular wall is avoided. The term Acentral member@ can bea member that simply blocks the distal opening of the catheter duringinflation of a balloon for percutaneous transluminal coronaryangioplasty; it may also be an embolization means such as a sackcontaining several occlusion coils, or a stent for expansion on aballoon, a sensor body for measuring pressure or temperature or thecomposition of blood, a physical shunt member, a retrieval wire or aforceps used to retrieve another member from a vascular site; or it canbe a central member of some other kind.

In another aspect, the number of wires may vary along the length of thecatheter, such as reducing the number of wires in the row during thewinding operation in the distal direction, enabling a larger pitch angleand increasing the flexibility of the catheter proximate to the distalend.

In a second embodiment, the medical device may be a delivery system fora prosthesis such as a stent, a stent graft, a valve member, or afilter, wherein the prosthesis is compressible to be placed within areceptacle at the distal end of the delivery catheter and is thenradially expandable upon delivery to a treatment site after being urgedfrom receptacle. The delivery system has a catheter shaft with areceptacle that may be simply a distal end portion of the cathetershaft, but the receptacle may also be a separate tubular member thatextends from the distal end of the catheter shaft, or optionallypartially within the distal end. The receptacle, whether integral withthe catheter shaft or a separate member, is primarily defined by a groupof wires wound about a lumen, thus having the same advantageousproperties of high flexibility and kink resistance as the cathetershaft; optionally and preferably, when the receptacle is a separatemember, the catheter shaft may also be of the inventive typehereinbefore set forth. The receptacle may have a larger lumen dimensionthan the lumen of the catheter shaft, such as by having a smaller wallthickness through use of smaller diameter wire or grinding away aninnermost portion of the coiled wires of the distal tip when integralwith the catheter shaft, since the wall thickness required for resistingthe outward pressure from the radially compacted prosthesis is smallerthan the wire thickness required to transmit axial thrust over a longshaft distance, such as 80 cm or more, enabling the outer diameter toremain the same as that of the catheter shaft portion.

In a third embodiment, a prosthesis receptacle is a separate member andis fixed to the helically wound multiple filament row of wires of thecatheter shaft, in axial extension thereof. This allows the prosthesisreceptacle to be designed and manufactured independently of the shaftportion. The mounting in direct extension of the wire or wires of thecatheter shaft makes the prosthesis receptacle follow torsional actionson the shaft portion. Although the prosthesis receptacle can be designedin any manner capable of resisting the outward pressure applied to theinside of the receptacle by the compressed prosthesis, it is preferredthat the prosthesis receptacle be a tubular segment of multiple filamentconstruction, such as a braided wire construction providing theprosthesis receptacle with a high flexibility. More preferably, thereceptacle is a construction of a second helically wound group or row ofmultiple wires; this makes it possible to obtain a very diminutive outerdiameter as only a single layer of wires is required.

In yet another embodiment, the medical device may be a pusher for use ina delivery system of the type described above, where the pusher isprimarily comprised of multiple wires that are helically coiled,resulting in a hollow construction with torqueability and pushabilitysimilar to the shaft portion of the delivery device and with slightlygreater flexibility due to the smaller outer diameter of the row ofwires.

In still another embodiment, the medical device may be used in anintroducer for an embolization device, where the delivery membercomprises primarily a plurality of wires to provide the advantageoustorqueability of the present invention. The distal end of the deliverymember thus is able to be rotated from rotation of the proximal endthereof, and thus being disconnectable through unscrewing from theembolization device, a technique that causes only negligible influenceon the vasculature while enabling precise maintenance of theembolization device in its desired position during detachment even invery tortuous paths to treatment sites such as intracranial locations.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is a side view of a catheter according to the present invention;

FIGS. 2 and 3 are enlarged partial views in longitudinal section ofembodiments of the catheter in FIG. 1;

FIG. 4 is a partial view in longitudinal section of an embodiment wherethe number of wires in a row varies along the length of the catheter;

FIG. 5 is an enlarged partial and sectional view of the transitionbetween two catheter segments having wires of different diameter;

FIG. 6 is an enlarged view of an embodiment having a catheter tip with abuffer member;

FIG. 7 depicts a winding operation on a multiple-wire row;

FIG. 8 depicts a catheter segment having decreasing outer diameters;

FIG. 9 is an illustration of the catheter of FIG. 1 in position in thevascular system;

FIG. 10 is an illustration of a device of the present invention used ina delivery system having a central member that serves as a pusher;

FIGS. 11 and 12 are enlarged views of central members of FIG. 10 beingadvanced out of the distal end of the catheter;

FIG. 13 is an illustration of a delivery system of the presentinvention, for delivery of a prosthesis such as a stent;

FIGS. 14 to 18 are enlarged partial views in longitudinal section ofvarious embodiments of the delivery system of FIG. 13;

FIG. 19 depicts a partial view of a delivery member of an embolizationdevice introducer according to the present invention;

FIG. 20 is a sketch of the introducer of FIG. 19 ready for disengagingan embolization device;

FIG. 21 is an enlarged illustration of the distal end of the deliverymember of FIG. 20 with an embolization device during placement in acatheter;

FIGS. 22 and 23 are partial view of the delivery members of otherembodiments of embolization device introducers;

FIG. 24 is an enlarged view of a coil connection means of FIG. 19;

FIGS. 25 and 26 are views of different embodiments of embolizationdevice introducers providing increased flexibility in the distal endarea of the delivery member; and

FIG. 27 illustrates delivering an embolization device by theembolization device introducer of FIG. 19.

DETAILED DESCRIPTION OF THE INVENTION

In the following description of the depicted embodiments, the samereference numerals are used for features of the same type. FIGS. 1 to 12illustrate luminal medical devices such as catheters and sheaths, FIGS.13 to 18 illustrate prosthesis receptacles and delivery systemstherefore; and FIGS. 19 to 27 illustrate embolization device deliverysystems.

vascular medical device according to the present invention andillustrated in FIG. 1 is generally denoted 1, and it has a distal end 2,a body portion 3 extending from the distal end to a proximal end 4. Thebody portion is made of a first helically wound multiple-filamentsequence, group or row of wires 5 and it has a central longitudinallyextending lumen 6. The medical device may be a catheter, and a catheteris normally open ended at both the proximal and the distal end; but forspecial uses such as a single lumen balloon dilatation catheter, thedistal end can be provided with means for barring the distal end opening(see FIG. 6).

For example, a catheter according to the present invention can be aballoon dilatation catheter used for percutaneous transluminal coronaryangioplasty, an angiography catheter, a drug delivery catheter, aguiding catheter, an infusion catheter, and so forth.

he wires 5 used in the helically wound multifilament group or row are ofa linear elastic material, such as stainless steel, titanium ortantalum, or it is made of a superelastic alloy, such as nitinol.Preferably, the wires have an ultimate tensile strength in the range of1800 to 2700 N/mm.sup.2 but lower or higher values are also possible.The body portion 3 of the catheter is made by placing a group of fromtwo to twelve wires of desired wire diameter in a row next or closelyadjacent to each other, whereafter the group of wires is wound accordingto the desired pitch angle in a common movement into the body portion.Because a row of wires is wound, an individual wire is restricted inmovement by the other wires and is plastically deformed into a permanenthelical shape which is kept without any further restraints other thanthe remaining wires in the row. The winding can be done on the insideend of a tubular support member where the row of wires is inserted atsaid end by rotating and simultaneously pushing the wires against theinside of the support. The wound wire then exits at the other end of thesupport. This produces a wire body with a very precise outer diameter.

Alternatively, the winding operation can take place about a mandrel 7.FIG. 7 depicts a winding of a row A of four identical wires 5. After thewinding the mandrel with the coiled wires can be subjected to heattreatment in order to remove residual stresses from the wires. As anexample the heat treatment can last for about two hours in an oven at atemperature of about 500° C. Generally, the temperature can be in therange of 400 to 600° C. and the holding time at the temperature can lastfor many hours, such as up to 20 hours or more. After the heat treatmentthe mandrel is removed from the wires. The wires in the resultinghelically wound multiple-wire group maintain their mutual position evenwhen heavily torqued, bent or pushed, presumably because each singlewire is supported by the contiguous wires in the row. The windingoperation can be effected so that the windings are touching each other,but preferably it is performed so that an interstice B is presentbetween the turns (FIG. 2). The interstice facilitates bending of thebody portion in tight turns along the vasculature such as is shown inFIG. 9.

The size of the pitch angle a (FIG. 2) depends on the diameter of thewires, the diameter of the body portion 3 and the number of wires in therow. The most preferred. pitch angle a for the catheter is in the rangeof 40° to 68° or 50° to 70°. However, the combination oftorque-transferral, pushability and transverse flexibility is normallywell-balanced for pitch angles in the range of 50° to 68°. The diameterd of the wire is typically in the range of 0.03 to 0.75 mm, andpreferably in the range of 0.15 to 0.45 mm. The present inventionincludes providing a medical device having different segments whereinthe row of wires is set to different pitch angles, or wherein differentrows of wires have different pitch angles.

In order to make the tip portion of the catheter more visible on ascreen it is desirable to use some kind of radiopaque material, such asplatinum or gold. It can be of annular shape and be located at apredetermined distance from the distal end 2, or the terminal end of thedistal tip of the catheter can be provided with a marker means formaking it radiopaque, such as a gold layer or a gold thread.

The catheter can be made with a uniform diameter throughout its length.In case the catheter has a diminishing diameter towards the distal end,a prefabricated catheter of uniform diameter can be ground to thedesired dimensions.

As an alternative or supplement to grinding, the catheter can becomposed of several segments in which the wires have mutually differentdiameters and cross-sectional areas. In a proximal segment 8 the wirescan have a larger diameter than the wires in a distal segment 9. Thesegments can be joined together in axial extension by laser welding 10as depicted in FIG. 5, by soldering, by bracing or in another mannersuch as mutual geometrically locking of the wires in the segments or bymechanical locking, such as press-fitting one segment into the lumen ofthe other segment, or binding the segments in axial extension withthreads or suture.

When the catheter body is of multi-segment construction, the innerlumens of the segments are preferably of even size which brings theadvantage that an advancing guidewire can not snag or grip onto a stepin the inner wall of the body portion.

In the embodiment illustrated in FIG. 4, the number of wires in saidhelically wound group or row of wires varies along the length of thecatheter. During the winding operation the number of wires in the row isreduced one by one at the points in time where the individual segmenthaving a certain number of wires has obtained the desired length. Thesegment marked AVI@ has six wires in the row, and the segments markedAV@, AIV@ and AIII@ have five, four and three wires, respectively, inthe row. Each time a wire is left out of the row, the pitch gets shorterand the pitch angle grows resulting in an even more flexible consecutivesegment. The advantage of this embodiment is that the wires extendinginto the distal end segment are continuous from the distal end to theproximal end of the catheter, thus avoiding any need for joining thevarious segments. It is possible to secure the wire ends of thediscontinuous wires onto the other wires, such as by welding, solderingor the like.

A grinding procedure can also be used to produce one or more taperedsegments 11 in the body portion 3 (FIG. 8). The taper can extend along asubstantial length of the body portion. In the tapered segment the outerdiameter of the catheter diminishes toward the distal end. Due to thetaper, the catheter obtains a gradually increasing transverseflexibility and a higher softness, but column strength and torque arenevertheless surprisingly transferred to the distal end.

When the catheter is to be advanced without a guidewire, the distal end2 can be provided with a soft buffer 12, as shown in FIG. 6, having arounded distal end which acts gently on the vascular wall when thecatheter is pushed forwardly. A thread 13 can be securely embedded intothe soft pliable material of buffer 12 and be ensnared around one of thedistal wires, so that the thread will keep the buffer connected to thecatheter body portion when the buffer is pushed out and cleared from thelumen of the catheter.

Referring now to FIG. 3, the wound wires 5 are provided with a sealingcoating 14 on the inside, or on the outside or on both, surfaces of thecatheter body. The coating is relatively thin and is preferably made ofan elastic material which can be hydrophilic. The coating extends alongthe entire length of the catheter and is typically applied after windingand heat treatment of the catheter body have been completed. As anexample, the coating can be of PTFE applied onto the outside surface ofthe body portion in the same manner as such a coating is traditionallyapplied onto the exterior of a guidewire. When the coating is to beapplied on the external and the internal surfaces of the body portionthe catheter length can be dipped briefly into a bath of liquid coatingmaterial, which is then allowed to solidify following removal from thebath.

In case it is desirable to use a hydrophilic coating, the coating cancomprise a hydrophilic polymer selected from the group comprisingpolyacrylate, copolymers comprising acrylic acid, polymethacrylate,polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide), poly(ethyleneimine), carboxymethylcellulose, methylcellulose, poly(acrylamidesulphonic acid), polyacrylonitrile, poly(vinyl pyrrolidone), agar,dextran, dextrin, carrageenan, xanthan, and guar. The hydrophilicpolymers can comprise ionizable groups such as acid groups, e.g.,carboxylic, sulphonic or nitric groups. The hydrophilic polymers may becross-linked through a suitable cross-binding compound. A cross-bindergenerally comprises two or more functional groups which provide for theconnection of the hydrophilic polymer chains. The actually-usedcross-binder depends on the polymer system: if the polymer system ispolymerized as a free radical polymerization, a preferred cross-bindercomprises 2 or 3 unsaturated double bonds.

By making the inventive device primarily of a group or row of two ormore wires, which row is helically wound with a pitch roughlycorresponding to the aggregate width of the adjacent wires in the row,the wound wires transfer torque and also force components directed inthe axial direction of the catheter to the distal end thereof, and thisconstruction is found to give a very high resistance to kinking of thedevice. When the device is heavily bent the cross-section of the devicemaintains a circular shape, and the forces transmitted through thehelically wound wires have less tendency to be concentrated in the areaof the bend. This is a distinct advantage over prior art devices of thetype that define a lumen (e.g., catheters and sheaths), which aredeformed into oval shape when bent, and thus they are much more prone tokinking. The device surprisingly maintains its capabilities fortransferring torque and push when it follows a tortuous path involvingtwo or more loops, probably because of the excellent kinking resistance;and in curved areas the torque and push is mainly transmitted within thedevice resulting in a favorably low influence on the vascular walls.

Due to the very high flexibility, pushability and torqueability and theability of the construction of the inventive device to maintain each ofthese three characteristics even when set in a very tortuous patterninvolving two or more tight loops, the device can be of use in verysmall and distant vessels such as deep brain sites accessed byintracranial catheterization.

If required, the flexibility of the distal portion of a luminal deviceduring advancement along a tortuous path, can be further increased byavoiding the use of a guidewire. The body portion of a catheter, forexample, can be maneuvered to the desired prosthesis deployment sitelike a guidewire because it is made of the multiple wire coils so interms of maneuverability there is no need for using the catheter inconjunction with a guidewire. However, a guidewire can be used todiminish the action of the catheter tip on the vascular wall because thetip will follow the guidewire when such is advanced in front of thecatheter prior to pushing the catheter forward. It is an advantage ofthe catheter according to the present invention that the wall isprimarily made of wires that provide a hard and relatively low-frictionor slippery inner surface resulting in low resistance to advancing amember through the lumen of the catheter.

When the catheter is used without a guidewire in a soft tissue region itis preferred that the distal end of the catheter is provided with abuffer member, such as a soft obturator. The buffer member distributesthe force from the catheter tip over a large area so that damage to thevascular wall is avoided.

In one embodiment the group or row of wires is made up of from 2 to 12helically wound wires, preferably of from 4 to 8 helically wound wires.By using several wires their aggregate width can be adapted tocorrespond to the desired pitch for the given diameter of the device. Arow of more than 12 wires would have a tendency to buckle when the wiresare helically wound in the common winding operation. For wires of roundcross-sectional shape a number of from 4 to 8 wires in the row ispreferred, but for flat wires or wires of oval shape two or three wiresin a row can be more suitable.

In order to promote uniform and well-defined characteristics of theinventive device along its length the wires in the row can be locatedclosely next to each other so that the mutually contact each otheralmost continuously and support each other. In this manner a possibledeflection of a single wire strand is reduced to a minimum by the otherswires in the row. As the wires in the row are wound into a helicalcourse in a common movement there can be an interstice between the turnsof the row of wires. The inside surface of an inventive catheter is alsomore even, which promotes advancing of a central member axiallytherewithin. The capabilities of torque and push are presumably a resultof a kind of mutual interlocking of the individual wire strands in thegroup or row of wires. If one wire in the row has a tendency to kink orbend heavily under influence of the load applied to the delivery member,the other wires in the row keep said wire in place because they are allextending in a common helical course, which interlocks the wires.

Where the inventive device is a delivery member for an embolizationcoil, after advancement of the introducer to the desired deploymentsite, a rotational movement at the distal end of the delivery member isimmediately transmitted into an almost identical rotational movement ofthe connection means at the distal end (viz., about 1:1 torquetransferral). Such an introducer is particularly useful in associationwith the connection means being designed for detachment by unscrewingfrom the embolization device, because the rotation of the deliverymember during unscrewing will cause only negligible influence on thevasculature, and the embolization device can thus easily be kept exactlyat the desired position during detachment, and furthermore there isobtained a very precise control of the detachment when, for example,three turns at the proximal end immediately results in an identicalthree turn rotation at the distal end of the delivery member.

In an embodiment the wires in said row have a pitch angle in the rangeof 26° to 76°, preferably a pitch angle in the range of 40° to 65°.Although it is possible to use other pitch angles, angles chosen inthese ranges provide a balanced solution to the requirements for thedesired high flexibility, high column strength and fine torqueability.The inner range of 40° to 65° is in particular useful for advancing acatheter to very distant, small sized vessels, such as in blood vesselsin the brain, whereas the subrange of 35° to 40° is applicable when veryhigh flexibility is a dominant requirement, and the subrange of 70° to76° is applicable when very high pushability is a dominant requirement.It is of course possible to choose different pitch angles in differentsegments of the device.

At the time of performing the winding operation of the body portion, theindividual wires in the row wound in the helical pattern have preferablya mainly circular cross-section. This facilitates the winding operationbecause twisting of a wire does not result in disorder in the row.

The sealing coating is preferably elastic. The wires are to a largeextent mutually locked in position because several wires are wound in acommon movement and thus one wire in the row is kept in place by theother wires in the row, but nevertheless some mutual movement can occurbetween the wires and in particular between the distal wire in one turnand the proximal wire in the consecutive turn. The sealing coating sealsthe interstices between the wires so that the catheter wall isleakproof. The elasticity of the sealing coating allows the wires toeffect small mutual movements so that the excellent flexibility of thehelically wound row of wires is maintained, and the elasticity alsoallows the catheter wall to stay leakproof when the wires move. Theelasticity is a particular advantage when the device is pulled back asthe pulling action can tend to elongate the body portion.

It is possible to provide the sealing coating only on the inner surfaceof the body portion which will result in a device of a very small wallthickness relative to its diameter. If a slightly enlarged diameter isacceptable, the coating can also or as an alternative be placed on theoutside of the body portion. The increase in diameter will be relativelymodest as the sealing coating can be made thin. The sealing coatingprovided on the outside of the body portion can, for example, result inno more than a 5 to 15% increase of the outer diameter of the catheterbody.

In an embodiment the sealing coating is a low-friction coating, such aspolytetrafluoroethylene (PTFE) coating. A low-friction coating appliedon the external side of the device wall acts to reduce the forcesrequired to push forward the device inside a larger guiding catheter ora sheath, and a low-friction coating applied on the internal side of thecatheter wall acts to reduce the forces required to push forward aguidewire or another member such as a pusher member advanced through thedevice.

In yet another embodiment the sealing coating is a hydrophilic coating.Such a coating can traditionally be applied to the exterior of a devicefor reducing the tendency of the device to stick to the vascular wall,but according to the present invention in addition to the lubricatingeffect of the coating it also effects the sealing of the body portion.The sealing coating is preferably thin and constitutes only a minor partof the wall thickness of the body portion. The thickness of the coatingat the middle of the wire can be less than 0.1 mm, and preferably it isless than 0.02 mm.

It is possible to promote the flexibility of the device by machining thewires in said row to a lesser outer diameter, e.g., by grinding, at aregion of the device. The region can extend along the whole length ofthe body portion, so that it is given a very precise outer dimension bythe machining. In another embodiment the region is a distal regionmachined to a tapering shape with decreasing outer diameter in thedistal direction causing the device to have an increasing flexibilitytowards the distal end which promotes the introduction into verydiminutive vessels. The reduced cross-sectional area of the wiresproduced by the machining greatly increases the bending flexibility ofthe device without sacrificing its ability to transfer torque.

Where the device of the present invention is utilized for delivery of aprosthesis such as a stent, it is preferred that at least in a 30 cmlong distal area the delivery system have a maximum outer diameter of3.0 mm, and suitably less than 2.0 mm. As use of a traditional separatesheet for keeping the prosthesis compressed can be wholly dispensed withbecause the prosthesis receptacle is in itself capable of keeping theprosthesis in the fully compressed state, the outer diameter of thereceptacle and the shaft portion is identical to the maximum outerdiameter of the delivery system portion introduced into the vascularsystem. A maximum diameter of 3 mm in the part of the device advancedthrough the vascular system allows for straightforward percutaneousintroduction by the Seldinger technique and easy navigation through thecurves in the larger vessels.

It is preferred that for most other forms of the invention, the deviceat least in a 30 cm long distal area, have a maximum outer diameter ofless than 2.0 mm. A maximum diameter of less than 1.00 mm allowsintroduction into quite fine and diminutive vessels such as into theexternal and internal carotid arteries. It is further possible torestrict the maximum outer diameter to at the most 0.75 mm which makesit possible to easily advance the inventive catheter into, for example,the liver or other soft tissue areas, and by keeping the maximum outerdiameter below 0.30 mm in a distal end area having a length of at least10 cm even the most distant vascular regions are accessible and thisembodiment of the catheter is excellent as a neuro-microcatheter.

When the inventive medical device is to be an embolization deviceintroducer, it is preferred that at least the distal area have a maximumouter diameter of 1.0 mm. A maximum diameter of 1.0 mm in the part ofthe embolization device introducer advanced through the vascular systemallows for a straightforward percutaneous introduction by the Seldingertechnique and easy navigation through the curves in the larger vessels.Coils having the relatively large diameters in the range of 0.7 to 1.0mm are suitable for embolization in larger vessels, and in particular atlocations where the blood flow rate is high, e.g., due to a malformationor trauma. A maximum diameter of 1.00 mm allows introduction into quitefine and diminutive vessels such as into the external and internalcarotid arteries.

In a further embodiment the number of wires in said helically woundgroup or row of wires varies along the length of the device. This can beattained by reducing, during the winding operation, the number of wiresin the row. The lower number of wires in the row can be utilized to windthe wires with a larger pitch angle which increases the flexibility ofthe device. It is preferred that the number of wires diminishes in thedistal direction so that the softness of the device increases withoutany change of material and without bonding together several separatedevice segments.

When the device has to traverse large lumen vascular paths in order toreach the more difficult small size vascular vessels, the helicallywound row of wires can be stiffened in a proximal segment of said bodyportion by a supplementary tubular member, such as a cannula tubing.

In the following, some examples of catheters are described that are madeaccording to the invention.

EXAMPLE 1

A catheter was made of a helically wound row of four wires of 0.35 mmwire diameter. The body portion of wound wires had initially an outsidediameter of 1.67 mm and an inner lumen of 0.97 mm. A coating of PTFE ofa minimum thickness of 0.1 mm was applied onto the inside of thecatheter. The catheter was set in a complex curved shape involving threeconsecutive loops of a loop diameter of 24 mm axially separated by twoloops of a loop diameter of 18 mm and a number of further turnsrepresentative of a complex vascular structure. Then the body portion ofthe catheter was manipulated and it proved to be easily pushed forwardand retracted as well as easily torqued. Then a guidewire was pushedforwardly in relation to the body portion, and it proved to be easilypushed out past the distal end of the catheter without causingnoticeable flexion or movement of the catheter.

EXAMPLE 2

A catheter was made of a helically wound row of five wires of 0.30 mmwire diameter. The winding of a first segment of the body portion wasmade with an outside diameter of 1.20 mm and an inner lumen of 0.6 mm.Another segment was made up of a second helically wound row of fourwires of 0.15 mm wire diameter. This segment had a length of 20 cm andan outside diameter of 1.20 mm and an inside diameter of 0.9 mm. Thesegments were joined by laser welding. The catheter body was providedwith a flexible coating on its outside. The catheter was advancedthrough a complex curved vascular system involving several consecutiveretrograde turns in vessels having a lumen of only 2 mm and less. Thenthe catheter was torqued and moved both forwardly and backwardly withoutany problems.

EXAMPLE 3

A catheter was made of a first helically wound row of eight wires of0.075 mm wire diameter. The winding was made with an outside diameter of0.25 mm and an inner lumen of 0.1 mm. The body portion had a length of160 cm and was coated with a hydrophilic material of polyacrylamide onits outside surface. When tested the catheter shows no problems. Afterplacing the catheter in a very complex pattern involving several sharpturns (see an example in FIG. 9), a guidewire could be advanced withonly very low friction, and after removal of the guidewire, a fluidcould be injected through the catheter without leakage through thecoating.

When the catheter is to be introduced into the vascular system there isfirstly established a percutaneous puncture site, e.g., by the Seldingertechnique, or an existing puncture site is used. Then the body or shaftportion of the catheter is inserted through the cannula, sheath orhemostatic valve at the puncture site and the catheter is advanced andnavigated through the vascular system to the treatment site or theprosthesis deployment site. Due to the very high flexibilility,pushability and torqueability of the catheter it can be advanced to thesite without use of a guidewire, or a sheath to negotiate the sharpcurves in the path. When large lumen vessels are to be traversed inorder to enter the vasculature near the target site, it can be anadvantage to stiffen the proximal portion of the catheter by insertingit through a cannula 14 (FIG. 3), a tubing or another kind of a morerigid structure.

The catheter according to the invention can be used as a traditionalcatheter, and it can also be used as a sheath which has normally ashorter length than a traditional catheter.

Individual features of the various embodiments can be combined intofurther embodiments according to the present invention. It is possibleto effect the sealing coating as a multilayer coating, e.g., comprisinga primer-coating and a top-coat where the primer-coating is chosen toprovide a strong bonding to the wires, and the top-coat provides thesealing action and can be a hydrophilic slippery coating providing a lowfriction surface.

A catheter system is illustrated in FIG. 10 to include a central member100 such as a pusher, and a catheter 1 having a distal end 2 and a bodyportion 3 extending from the distal end to a proximal end 4, thecatheter being similar to catheter 1 of FIG. 1. The central member maybe used to block the distal opening during inflation of a balloon of aballoon dilatation catheter for percutaneous transluminal coronaryangioplasty. The catheter system can also be for placing the centralmember in the vascular system. To give some examples, the center membercan include (or can be) an embolization means in the form of a sack 102containing several occlusion coils, as shown in FIG. 11. It also can bea stent for expansion on a balloon, or it can be a sensor body formeasuring pressure or temperature or the composition of blood, or it canbe a physical shunt member. It also can be or include a retrieval wireor a forceps 104, as shown in FIG. 12 used to retrieve another memberfrom a vascular site, or it can be a central member of some other kind.

Following are three examples of catheter systems made according to theinvention.

EXAMPLE 4

A catheter was made in accordance with the catheter of Example 1 anddeployed in the complex vascular structure described therein. Then a bag102 with four occlusion coils was pushed forward by the pusher 100 (FIG.10) until it discharged through the opening at the distal end 2, asshown in FIG. 11. There was no noticeable sticking of the bag 102against the inside surface of the catheter.

EXAMPLE 5

A catheter was made in accordance with the catheter of Example 2 andprovided with a PTFE coating on its outside surface. The catheter wasadvanced through a complex curved vascular system involving severalconsecutive, retrograde turns in vessels having a lumen of only 2 mm andless. Then a pair of forceps 104 was advanced through the catheter asshown in FIG. 12, and activated to grab the desired item, such as akidney stone, and retracted through the catheter lumen.

EXAMPLE 6

A catheter was made having the wire structure and dimensions of thecatheter in Example 3. The body portion was uncoated, and when testedthe catheter showed no problems. After placing the catheter in a verycomplex pattern involving several sharp turns (see an example in FIG. 9)a guidewire could be advanced with only very low friction, and afterremoval of the guidewire, central members in the form of fluid injectedembolization coils were delivered through the catheter.

Shown in FIGS. 13 to 18 is a delivery system according to the presentinvention, for use in the delivery of a prosthesis to a treatment sitein the vasculature. The prosthesis may be of the radially compressible,self-expandable type such as a stent, a stent graft, a valve member or afilter, and may be formed of shape memory alloy. When the deliverysystem has been maneuvered to the desired location, the prosthesis isdischarged by application of a pushing force against the proximal end ofthe prosthesis relative to the delivery system by means of a pushermember; alternatively, the prosthesis may be discharged by being held bya trigger wire against proximal movement as the surrounding catheter orsheath is pulled proximally.

Delivery system 200 in FIG. 13 includes a delivery device 202 having adistal end 204 and a shaft portion 206 extending between a prosthesisreceptacle 208 at the distal end and a proximal mounting member 210fixedly mounted to the shaft portion. The shaft portion is made of afirst helically wound multiple filament row of wires 212 and it has acentral longitudinally extending lumen 214.

The delivery system 200 further comprises a pusher member 216 which canbe inserted through the lumen 214. A handle or pin vise 218 is mountedon the pusher member for pushing it forwardly in the distal directionwhen a prosthesis 220 located in receptacle 208 is to be released fromthe introducer device by being pushed out of receptacle 208. Pin vise218 and mounting member 210 can be parts of a unitary control device tobe manually actuated when the prosthesis has been introduced andpositioned at the desired vascular site.

At the distal end of the pusher member 216 an engagement means 222 canact on the prosthesis 220. The engagement means can be for example aplate of a dimension fitting into receptacle 208 and abutting theproximal end of the prosthesis so that the plate pushes the prosthesisout of the receptacle when the pusher member is pushed forwardly. Theengagement means can also be designed as an elongate member that extendscoaxially inside the radially compressed prosthesis and engages theprosthesis at several locations along the length thereof so that theprostheses is partly pulled, partly pushed out of the receptacle. Theseengagement points or areas can be effected by radial projections, hooks,ridges, or another kind of engagement means such as a high frictionmaterial. This can be an advantage if the prosthesis has an extensivelength, and in particular if it has a construction having a tendency tobuckle when pushed upon.

By the term Aprosthesis receptacle@ is meant any structure or regionnear or at the distal end of a delivery device where a radiallycompressible tubular prosthesis is carried during maneuvering of thedelivery device and prosthesis within a body lumen. The prosthesisreceptacle 208 can be made of a length of tubular material that isflexible in itself or is made flexible by incisions or due to itsconstruction, such as a construction of wound or braided wires. If theprosthesis is rather short in length or is for deployment in a largesized vessel of a rather straight shape, such as in the aorta, thereceptacle need not be flexible and can be made out of a stiff tubularmember.

The length of the prosthesis receptacle 208 is at least of the same sizeas the length of the loaded prosthesis 220. However, other lengths arealso possible As depicted in FIG. 18, the receptacle 208 can have alength that is considerably longer than the loaded prosthesis 220, sothat the prosthesis can be loaded into a position at the proximal end ofthe receptacle leaving empty a distal length of the receptacle. Thisfree distal length will not be stiffened by the presence of the loadedprosthesis and will consequently be very soft and flexible. The lengthcan for example by chosen so that the free distal length is in the rangeof from 5 to 150 mm, preferably in the range of 10 to 50 mm.

In a preferred embodiment, the prosthesis receptacle 208 is made of asecond helically wound multiple filament row of wires 224. As depictedin FIG. 14, the second row of wires 224 can be made independently of thefirst row of wires 212 and in different dimensions or differentmaterials than the first row of wires, and the receptacle 208 is thenfixed in axial extension of the first row of wires, e.g., by laserwelding, soldering bracing, or mechanical locking such as press-fittinginto the lumen of the shaft portion, or binding with threads or suture.An alternative embodiment is depicted in FIGS. 15 and 16 whereprosthesis receptacle 208 is made integral with shaft portion 206 byusing a distal segment 226 of said first row of wires 212 as thereceptacle.

In the embodiment of FIG. 15, the inner lumens in the shaft portion 206and in receptacle 208 are of even size which brings the advantages ofbeing able to load prostheses of various lengths in one and the samedelivery system and of being able to lead from the proximal end of thedelivery device a pusher member having a solid engagement means 222 of adiameter that is only slightly less than the diameter of the inner lumen214.

In the embodiment of FIG. 16, the pusher member 216 is inserted from thedistal end of the shaft portion prior to leading the prosthesis 220 intoreceptacle 208. This allows the engagement means 222 to be of a largerdiameter than the lumen 214 of shaft portion 206.

In the embodiment of FIG. 18, the radially compacted prosthesis 220projects radially inwards beyond the step in inner lumen diameter at thetransition between receptacle 208 and shaft portion 206. Consequently,it is possible to use a pusher member 216 having an engagement member222 of less diameter than lumen 214 and yet push the prosthesis out ofreceptacle 208 by its pressing against the proximal end of theprosthesis.

The shaft of the pusher member 216 can be of a small diameter solid wireor rid as depicted in FIG. 15 or it can be made of a third helicallywound multiple filament row of wires 228 as depicted in FIG. 14. Thereceptacle 208 in the embodiment of FIG. 16 is made by machining theinside of the wound wires 226 to a larger lumen. This can for example bydone by spark erosion or grinding. In the latter case, the distal endportion of the wound wires are placed in a retaining ring (not shown)that is longitudinally displaceable with respect to a coaxially mountedgrinding wheel.

A grinding procedure can also be used to produce a tapered section 230in shaft portion 206 (seen in FIG. 17). The taper can extend along asubstantial length of the shaft portion. In the tapered section theouter diameter of the delivery device 202 diminishes to diameter D2. Dueto the taper the delivery device obtains a gradually increasingtransverse flexibility and a higher softness, but torque is neverthelesssurprisingly transferred fully to the receptacle 208. As an alternativeor supplement to grinding, the shaft portion 206 can be composed ofseveral portions in which the wires of each portion have mutuallydifferent diameters and cross-sectional areas.

Preferably, the distal tip of the delivery system is provided withmarker means 230 for making it radiopaque, e.g., by a gold or platinumplating, or by soldering, brazing or laser welding a radiopaque memberonto the distal tip (FIG. 17). The marker 230 promotes precisepositioning of the prosthesis at a treatment site in the vasculature.

For some applications it is desirable to deploy a prosthesis that hasbeen provided with an active substance, such as a cell growth inhibitor.The active substance can have such a short shelf life that it needs tobe applied to the prosthesis immediately prior to deploying theprosthesis. This can be done by dipping the distal end of the deliverydevice, viz., the prosthesis in the receptacle, into a fluid of activesubstance.

Following are some examples of delivery systems made according to theinvention:

EXAMPLE 7

A delivery device was made of a first helically wound row of four wiresof 0.35 mm wire diameter. The shaft of wound wires had initially anoutside diameter of 1.67 mm and an inner lumen of 0.97 mm. Thereceptacle was made up of a second helically wound row of four wires of0.20 mm wire diameter. The receptacle had a length of 37 mm andinitially an outside diameter of 1.70 mm and an inside diameter of 1.3mm. A radially compressed stent was arranged inside the receptacle. Theloaded stent had a length of 35 mm and was recessed a little in relationto the distal end of the receptacle. The pusher member was made of athird helically wound row of four wires of 0.28 mm wire diameter and ashaft outer diameter of 0.91 mm. A plunger element or an engagementmember was located on the distal end of the shaft. The shaft and thereceptacle of the delivery device was ground to a common outer diameterof 1.5 mm (4.5 French). In its fully self-expanded state the stent hadan outer diameter of 8 mm. The delivery device was set in a complexcurved shape involving three consecutive loops of a loop diameter of 20mm axially separated by two loops of a loop diameter of 15 mm and anumber of further turns representative of a complex vascular structure.Then the shaft of the delivery device was manipulated and it proved tobe easily pushed forwardly and retracted as well as easily torqued. Thenthe pusher member was pushed forwardly in relation to the shaft portion,and the stent was easily pushed out of the receptacle without causingnoticeable flexion or movement of the delivery device.

EXAMPLE 8

A delivery device was made of a first helically wound row of five wiresof 0.30 mm wire diameter. The winding of the shaft was made with anoutside diameter of 1.20 mm and an inner lumen of 0.6 mm. The receptaclewas made up of a second helically wound row of four wires of 0.15 mmwire diameter. The receptacle had a length of 60 mm and an outsidediameter of 1.20 mm and an inside diameter of 0.9 mm. A radiallycompressed prosthesis was arranged inside the receptacle. The loadedprosthesis had a length of 20 mm and was positioned at the proximal endof the receptacle with a 40 mm very soft free distal receptacle end. Thepusher member was made of a single 0.35 mm diameter wire rod thatcarried an engagement member at its distal end. In its fullyself-expanded state the prosthesis had an outer diameter of 3 mm. Thedelivery device was advanced through a complex curved vascular systeminvolving several consecutive, retrograde turns in vessels having alumen of only 2 mm or less. Then the pusher member was pushed forwardlyin relation to the shaft portion, and the stent was easily pushed out ofthe receptacle in a well-controlled manner.

EXAMPLE 9

A combined receptacle and distal shaft segment of a delivery device wasmade of a first helically wound row of eight wires of 0.075 mm wirediameter. The winding was made with an outside diameter of 0.25 mm andan inner lumen of 0.1 mm. The combined receptacle and distal shaftsegment had a length of 12 cm. A prosthesis was compressed radially toan outer diameter of 0.07 mm and was pushed into the receptacle. Theloaded prosthesis had a length of 10 mm and was positioned in thereceptacle with its proximal end 25 mm from the distal receptacle end.The pusher member was made of a single 0.08 mm diameter solid wire rod.The pusher member was used to push the stent out of the receptacle.

Shown in FIGS. 19 to 27 is a delivery system for an embolization coil,made according to the present invention. A delivery system 300 has alength in the range of 50 to 250 cm and a diameter in the range of 0.08to 2.0 mm, depending on the relevant field of application. The deliverysystem utilizes a delivery member 302 within an introducer 304, and in adistal section 306 the delivery member has a connection means 308 for anembolization device 310.

The delivery system may utilize any of a number of kinds of connectionmeans 308, among which are: an electrolytically erodable means, a heaterodable means, a latch, a coupling, a threading coil, a thread, adeflatable balloon, and a hydraulically or pneumatically activatedgripper means. As shown in FIG. 19, the delivery member 302 preferablyhas in its distal section 306 a central core 312 with a blade-shapedportion, and the connection means 308 is a threading coil 314 which isfixed to the central core at least at the edges of the blade-shapedportion. The blade-shaped portion carrying the threading coil is muchmore flexible and easy to bend in the thickness direction of the bladethan in the direction of the width where the blade dimension is thelargest. The blade-shaped portion is a distal end portion 316 of thecentral core 312 and if it is subjected to a torque, the central coretwists. When the delivery wire is advanced and has to pass through acurvature, the blade-shaped portion touches the inner wall of the lumenand is subjected to a torque until the blade-shaped portion has turneditself with the direction of width transverse to the curvature. Theresult is that the bending occurs in the thickness direction which ismost flexible. The fixation of the threading coil 314 at the edgesprovides control of the positioning of the threads so that theunthreading of the embolization device 310 is very smooth-running.

The connection means 308 can be made of radiopaque material in order tobe discerned on an image screen by the radiologist or neuroradiologistthat introduces the detachable embolization device 310 into the vascularsystem of a patient, but in order to be seen clearly the radiopaque areaought to have relatively large dimensions. This can be obtained bypositioning a radiopaque marker at a predefined first distance, such asabout 3 to 3.5 cm, proximal to the distal termination of the connectionmeans 308. In this embodiment, the connection means in itself need notbe radiopaque, because the marker is clearly seen and the radiologist isaware that the embolization device is positioned said first distanceahead of the marker.

In the following description of several embodiments, the same numeralsare used to denote features of the same kind. In one embodiment theconnection means 308 comprises a central core 312 of stainless steel,nitinol, or another suitable material and a threading coil 314. Thecentral core 312 has at its distal end section 316 a blade-shapedportion with a blade thickness and a blade width, which is more thantwice as large as the blade thickness. The threading coil 312 is fixedonto the blade-shaped portion, e.g., by soldering, welding, brazing orgluing at joints 346 (as seen in FIG. 23). The threading coil wire canbe of stainless steel and can have a wire diameter in the range of 0.02to 0.12 mm, typically a diameter of about 0.06 to 0.075 mm. The wire isset with a pitch corresponding to or being larger than twice thethickness of the wire so that a mating threading in the proximal end ofthe detachable embolization device 310 can be threaded into and out ofthreading coil 314, as shown in FIG. 24. The outer diameter of thethreading coil can, for superselective use, be in the range of 0.08 to1.0 mm, and typically from 0.20 to 0.45 mm.

Other embodiments of the connection means 308 include a connecting area,which is eroded away by applying current or head when the embolizationdevice 310 is positioned at the desired site, or a latch or a couplingproviding a geometrical locking, such as a bayonet coupling, two matingparts held together by a thread that can be pulled out for detachment ofthe embolization device, or a deflatable balloon positioned inside atubular proximal end area of the embolization device 310. Otherembodiments of threads can also be used, such as spaced ball-likeenlargements on the central member, a helix-shaped groove cut into acylindrical or conical distal end part on delivery member 302. Thesekinds of connection means are well known in the art, e.g., from EP-A-0720 838; U.S. Pat. No. 5,217,484; WO 94/06503; WO 94/06502; WO 94/00104;and EP-A-0 717 969. In FIG. 23 such a connection means 308 is shown in ageneral manner, and an activation member 318 is shown to extend insidethe delivery member 302. The activation member can be, for example, theabove mentioned thread to be pulled out, an optical fiber, an electricalwire, and so forth.

The embolization device 310 can be a Gianturco stainless steel coil oftraditional design, or coils with a regular helical shape or irregularcoil shape as described in U.S. Pat. No. 4,994,069; U.S. Pat. No.5,122,136; WO 93/06883; WO 94/11051; WO 94/07560; WO 94/10936; WO95/25480; DE-295 18 932-U1; WO 96/18343; EP 0 623 012 or theembolization device can be a random matrix shape as described in U.S.Pat. No. 4,994,069 and WO 94/09705. The embolization device can also beof a regular linear shape as described in WO 98/09570, which is herebyincorporated into the present description by reference. The embolizationdevice can also be called an occlusion device.

Referring now to FIGS. 20 and 21, placement of the embolization device310 in an aneurysm 320 will be described. A catheter is introducedpercutaneously through a fitting 322 by the Seldinger technique andadvanced transluminally in a well known manner along a suitable pathuntil the distal end of the catheter is located in the neck of theaneurysm 320. Then an introducer 304 with the embolization device 310mounted on the delivery member 302 is inserted into the catheter andpushed forwardly until the embolization device is pushed out of thecatheter and is in the desired deployment position in aneurysm. Sopositioned, the delivery member extends along a complexly curved path.Then the embolization device is released from connection means 308. Thiscan be done, for example, by activating member 318 or by rotating theproximal end of the delivery member with the aid of a pin vise 324 whichis fixed onto a proximal section 326 of delivery member 302.

Referring now to FIGS. 22 to 27, wires 330 are wound by a windingoperation in a manner such as that described with respect to FIG. 2. Thewinding operation can be effected so that the windings are touching eachother, but preferably it is performed so that a slight interstice B ispresent between the turns (FIG. 23). The interstices facilitate bendingof the body portion in tight turns of the vasculature (FIG. 20). Thesize of the pitch angle depends on the diameter of the wires, thediameter of the delivery member 302 and the number of wires in thesequence, group or row. The most preferred pitch angle for the deliverymember is in the range of 40° to 65°. However, the combination oftorque-transferral, pushability and transverse flexibility is normallywell-balanced for pitch angles in the range of 50° to 68°. The diameterof the wire is typically in the range of 0.03 to 0.75 mm, and preferablyin the range of 0.15 to 0.45 mm.

In order to make the tip portion of the delivery member more visible ona screen, it is desirable to use some kind of radiopaque marker 332 orradiopaque material, such as platinum or gold. It can be of annularshape and be located at a predetermined distance c from the distal end334, as shown in FIG. 22. The marker can be of platinum wire insertedinto delivery member 302 in distal extension of wires 330, or it can bea separate member such as a platinum or gold ring. A catheter 336 usedwhen advancing the introducer 304 can also have a radiopaque marker 338located at such a distance from the distal end 340 of the catheter thatthe embolization device 310 is in position for release when the marker332 has been advanced to be positioned at marker 338.

In the embodiment illustrated in FIG. 23 the number of wires 330 inportions of the length of the delivery member 302 varies along thelength. During the winding operation the number of wires in the group isreduced one by one at the points where individual portions having aconstant number of wires have obtained their desired lengths. Thesegments marked V, IV and III have five, four and three wires,respectively, in the group. Each time a wire is left out of the group,the pitch gets shorter and the pitch angle grows resulting in an evenmore flexible consecutive segment. The advantage of this embodiment isthat the wires extending into the distal end segment are continuous fromthe distal end to the proximal end of the delivery member, thus avoidingany need for joining the various portions. It is possible to secure thethread ends of the discontinuous wires onto the other wires, such as bywelding, soldering and so forth.

The delivery member can be made with uniform diameter throughout itslength. Incase the delivery member is to have diminishing diametertoward the distal end, a prefabricated delivery member of uniformdiameter and be ground to the desired dimensions. As an alternative orsupplement to grinding, the delivery member can be composed of severalsegments in which the wires have mutually different diameters andcross-sectional areas, as described with respect to FIG. 5.

As illustrated in FIGS. 25 and 26, a grinding procedure can also be usedto produce one or more tapered segments 340, 342 in delivery member 302.The taper can extend along a substantial length of the delivery memberto produce a gradually increasing flexibility. In the tapered segments,the outer diameter of the delivery member 302 diminishes toward thedistal end 334. Due to the taper or tapers, the delivery member obtainsa gradually increasing transverse flexibility and a higher softness, butcolumn strength and torque are nevertheless surprisingly transferred tothe distal end.

In the embodiment of FIG. 22, the wound wires 330 are provided with alow-friction coating 344 on the radially outwardly facing surface ofdelivery member 302. The coating is relatively thin and is preferablymade of an elastic material which can by hydrophilic. The coatingextends along part of or along the entire length of the delivery memberand is typically applied after winding and heat treatment of thedelivery member have been completed. As an example, the coating can beof PTFE applied onto the outside of the body portion in a traditionalmanner.

The helically wound row of wires in the delivery member makes itpossible to manufacture the connection means as an integral part of thedelivery member. This can be done by removing one or several of thewires in the distal end portion of the delivery member. The wires arevery diminutive so that they can be cut, for example, by a laser beam ormanually with a tool under a microscope. If required, a thread cuttertool or a thread shaping tool can be used to set the remaining wire orwires with the desired pitch corresponding to the pitch on the matingcoupling member on the embolization device. The resulting unitarydelivery member has in its distal end only the wires which extend towardthe proximal end.

Following are several examples of delivery members made according to thepresent invention:

EXAMPLE 10

A delivery member was made of a helically wound row of four wires of0.30 mm wire diameter. The delivery member had initially an outsidediameter of 0.90 mm. The delivery member was set in a complex curvedshape involving three consecutive loops of a loop diameter of 24 mmaxially separated by two loops of a loop diameter of 18 mm and a numberof further turns representative of a complex vascular structure. Thenthe proximal section of the delivery member was manipulated and itproved to be easily pushed forward and retracted as well as easilytorqued.

EXAMPLE 11

A delivery member was made of a helically wound row of five wires of0.25 wire diameter. The winding of a first segment of the deliverymember was made with an outside diameter of 0.80 mm. Another segment wasmade up of a second helically wound row of four wires of 0.15 mm wirediameter. This segment had a length of 20 cm and an outside diameter of0.45 mm. The segments were joined by laser welding. The delivery memberwas provided with a coating on its outside surface. The delivery memberwas advanced through a complex curved vascular system involving severalconsecutive, retrograde turns in vessels having a lumen of only 2 mm andless. Then the delivery member was torqued and moved both forwardly andbackwardly without any problems.

EXAMPLE 12

A delivery member was made of a first helically wound row of eight wiresof 0.075 mm wire diameter. The winding was made with an outside diameterof 0.25 mm. The delivery member had a length of 160 cm. When tested, thedelivery member showed no problems. After placing the delivery member ina very complex pattern involving several sharp turns, the distal endcould be rotated in a 1:1 relationship with a rotation of the proximalend of the delivery member.

1-35. (canceled)
 36. A delivery system comprising: a delivery devicewith a distal end and a shaft portion with a lumen extending in alongitudinal direction from a proximal end and toward the distal end, aself-expandable prosthesis arranged in a receptacle at the distal end ofthe delivery device, and a pusher member arranged in the lumen of saiddelivery device to cause relative axial movement of the self-expandableprosthesis with respect to the delivery device, said shaft portion ofsaid delivery device comprising a first helically wound multiplefilament row of from four to eight wires of circular cross-sectionclosely adjacent to each other, wherein said row of wires has a pitchangle in the range of 40° to 65°, the wires being provided with alow-friction sealing coating of elastic material on at least a radiallyoutwardly facing surface, the sealing coating having a thickness at themiddle of each of the wires of less than 0.1 mm, said receptaclecomprising a second helically wound multiple filament row of from two totwelve wires of circular cross-section closely adjacent to each other,wherein said row of wires has a pitch angle in the range of 26° to 76°,said pusher member comprising a third helically wound multiple filamentrow of from two to twelve wires of circular cross-section closelyadjacent to each other, wherein said row of wires has a pitch angle inthe range of 26° to 76°, and one of a radially inwardly facing surfaceof said delivery device and a radially outwardly facing surface of saidpusher member being provided with a low-friction sealing coating ofelastic material.
 37. (canceled)
 38. An embolization device introducercomprising: a delivery member having a proximal section, and a distalsection with a connection means for detachably mounting of anembolization device, wherein the delivery member comprises a multiplefilament helically wound row of four to eight closely adjacent wiresextending from said distal section toward the proximal section of thedelivery member, wherein said row of wires has a pitch angle in therange of 40° to 65°, the wires being provided with a low-frictionsealing coating of elastic material on at least a radially outwardlyfacing surface, the sealing coating having a thickness at the middle ofeach of the wires of less than 0.1 mm.
 39. An embolization deviceintroducer comprising: a delivery member having a proximal section, anda distal section with a connection means for detachably mounting of anembolization device, wherein the delivery member comprises a multiplefilament helically wound row of wires extending from said distal sectiontoward the proximal section of the delivery member.
 40. An embolizationdevice introducer as in claim 38, wherein the connection means includesan electrolytically erodable means.
 41. An embolization deviceintroducer as in claim 38, wherein the connection means includes a heaterodeable means.
 42. An embolization device introducer as in claim 38,wherein the connection means includes a threading coil for threadingengagement with the embolization device.
 43. An embolization deviceintroducer as in claim 38, wherein the distal section of the deliverymember includes a radiopaque material.
 44. An embolization deviceintroducer as in claim 43, wherein the radiopaque material is spaced apredetermined distance from a distal end of the connection means.
 45. Anembolization device introducer as in claim 43, wherein the radiopaquematerial is at least a portion of the connection means.
 46. Anembolization device introducer as in claim 39, wherein the connectionmeans includes an electrolytically erodable means.
 47. An embolizationdevice introducer as in claim 39, wherein the connection means includesa heat erodeable means.
 48. An embolization device introducer as inclaim 39, wherein the connection means includes a threading coil forthreading engagement with the embolization device.
 49. An embolizationdevice introducer as in claim 39, wherein the distal section of thedelivery member includes a radiopaque material.
 50. An embolizationdevice introducer as in claim 49, wherein the radiopaque material isspaced a predetermined distance from a distal end of the connectionmeans.
 51. An embolization device introducer as in claim 49, wherein theradiopaque material is at least a portion of the connection means.